Many different types, shapes and components of samplers for molten metal have been developed or proposed in recent years. These include the samplers disclosed in my previous U.S. Pat. Nos. 3,457,790; 3,452,602; 3,686,949; 4,046,016; 4,499,777 and 4,453,424. The foamed ceramic or castable silicate compositions described in my U.S. Pat. No. 3,561,494 provide excellent heat insulating coatings protecting samplers and lance tubes from the high temperature molten metal during the sampling operation, and assuring proper chilling of the melt samples.
A sampler for molten metal must provide a sampling chamber or cavity enclosed inside a hollow chill mold, which is provided with slots or vents capable of venting the air displaced by the inrushing molten metal. Surrounding insulating material, such as a foamed ceramic chamber or coating, preserves the chill mold at a temperature far below that of the molten metal for a period long enough to chill the inrushing molten sample to the consistency of slush. The sampler is then removed from the melt, and cooling is continued by exposure to the atmosphere at room temperature, or to a quenching bath of water or liquid nitrogen, for example.
The solidified samples are then readily removed from the chill mold for prompt metallurgical analysis, facilitating immediate adjustment of the melt composition as often as required while still in its molten state.
The samplers of these previous patents produce reliable and homogeneous samples whether they are used in deep immersion sampling operations, killed steel sampling operations requiring no deoxidizing treatment, or sampling of unkilled steel with deoxidants carried inside the sampler being dispersed and dissolved in the inrushing molten metal as the sampling operation is performed. Metallic deoxidants such as aluminum, zirconium, magnesium, or titanium are preferably formed in the shape of a helical coil of wire, positioned just inside a slag cover at the intake portal of the sampler, as illustrated in FIG. 11 of my U.S. Pat. No. 4,499,777.
Sampling of low temperature melts, such as those just at or above the "liquidus" or "freezing" temperature at which the molten metal begins to solidify, imposes unique problems. The sampler must be protected from the effects of floating slag which must not be allowed to freeze on the cold sampler and block the sampling operation. At the same time, the metal slag cover protecting the intake portal of the sampler must not be so thick as to retard the melting of the slag cover and thus unnecessarily delaying the entrance of the molten metal to be sampled to the interior of the sampling chill mold.
Accordingly, a principal object of the present invention is to provide highly effective molten metal sampling for use in relatively low temperature molten metal.
Another object of the invention is to provide sampler devices capable of such sampling with metal slag covers over their intake portals which are readily melted away, even by the low temperature molten metal.
A further object of the invention is to provide such samplers in which the metal slag covers are enclosed in protective jackets capable of explosive slag deflection during the immersion of the sampler in the melt.
A still further object of the invention is to provide such samplers incorporating a predetermined volume of deoxidant material encircling the intake portal inside the metal slag cover.
Other objects of the invention will in part be obvious and will in part appear hereinafter.
The invention accordingly comprises the features of construction, combinations of elements, and arrangements of parts which will be exemplified in the constructions hereinafter set forth, and the scope of the invention will be indicated in the claims.